Abstract: Since discovery of the deep biosphere in the 1990’s, comprehensive knowledge of prokaryotes have created a new area of scientific investigation because deep-sea sediments represent a novel biosphere comprising global carbon cycle with phylogenic lineages of domain Archaea and Bacteria. Recent sub-seafloor studies among Integrated Ocean Drilling Program (IODP) revealed that past organic matter content in the sediment could represent a crucial factor in the growth and reproduction of heterotrophic sub-seafloor Archaea. As the putative predominant archaea are viable but non-cultureable and on-shore laboratory studies remain problematic, we are developing a new organic geochemical tool to compensate the limitation toward a next milestone of deep biosphere studies.

Abstract: Recent cultivation-independent molecular studies showed that phylogenetically diverse microbes are present in marine subsurface environments. However, these microbes, especially for major microbial components and key-biogeochemical players including methanogens, have been highly resistant to in vitro cultivation. For the successful cultivation of these recalcitrant marine subsurface microbes, I used a continuous-flow bioreactor system that has been often used for treatment of municipal wastewater. Using the bioreactor, I have successfully made a methanogenic microbial community from marine subsurface sediment after 1 year of the reactor operation. The microbial community contained phylogenetically diverse microbes including uncultured methanogens.

Abstract: Since its discovery in 1791, dolomite, the mineral and the rock, has stimulated much research. Despite a profusion of hypotheses and idealized models for dolomite formation, the specific conditions for its origin have remained and enigma. Recently, a new geomicrobiological approach has been applied to the study of modern and ancient dolomite offering an actualistic solution for the long-standing Dolomite problem.

演題：浮遊生物生態系機能・生物多様性の地球規模調査システム開発
(Development of a system to survey planktonic diversity and ecosystem functioning on a global scale)

Abstract：
In this talk I will explain the background behind why such a system is
necessary as well as the steps that have already been taken towards
the development of such a system. There will be an introduction to
cutting edge survey techniques using imaging technology, DNA barcoding
and traditional taxonomic methods, real data from Antarctica, and a
vision towards the development of new infrastructure to realize the
goal of the next phase of the Census of Marine Life.

(English)
Title: Microbial genome in extremobiosphere
Abstrabt:
We have been investigating on genome analyses of Extremophiles,
namely Bacillus halodurans C-125 and two Bacillus related strains.
Since then, based on the technique and information of genome analysis,
we are studying on activities and evolution of deep-sea
microorganisms. Our studies usually concentrated on what we can know
or understand through whole genome analysis. Recently, we found genes
involving N-linked glycosylation in the genome of
Epsilonproteobacteria, which develops into a study on communication
via carbohydrate chains between bacteria and invertebrate in deep-sea
chemosynthetic symbioses. We also formulated a hypothesis about genome
reduction process upon genome comparison of two deep-sea Calyptogena
symbionts. In this seminar, I describe an interesting genome research
in extremobiosphere.

(English)
Title: Compound-specific stable isotope analysis of organic compounds and its
application to biogeochemistry
Abstract:
One of the most powerful tools in the molecular isotope studies is
compound-specific isotope analysis (CSIA) by gas chromatograph/isotope ratio
mass spectrometer (GC/IRMS), which allows a rapid and precise determination
of stable carbon, nitrogen, and hydrogen (and oxygen) isotopic compositions
of individual compounds even in complex mixture of components.In this
seminar, I will review this tool briefly and show a recent application to
ecological studies: estimation of the trophic level of organisms in food
webs.

(English)
Title: Studies on fungi in deep-sea environments
Abstract:
Fungi are one of the most important components in ecosystems and
they occupy a wide variety of environments by virtue of their highly
versatile physiology function. Although the presence of fungi in deep-
sea environments has started to be recognized, its distribution and
diversity are still largely unknown. Environmental gene library
analyses of deep-sea sediments have recently demonstrated the presence
of diverse highly novel fungi, including new taxonomic groups that may
be relevant to the early evolution of fungi.
Our research team has also started to work on deep-sea delivered
fungi for application use. We believe that fungi in deep-sea
environments hold great potential for both science and industry.

(English)
Title: Molecular characterization of benthic foraminifer Virgulinella fragilis to
understand the survival strategy in oxygen-depleted environment)
Abstract:
Molecular phylogenetic analyses and ultrastructural observation were
conducted in order to understand the survival strategy of Virgulinella
fragilis, a benthic foraminifer restricted to dysoxic environments.
Many benthic foraminifers can persist in sediment in dysoxic
environments. Some of them probably live in symbiosis with bacteria
that can denitrificate and also putatively oxidize sulfide.
Observations of endosymbiotic bacteria and kleptoplasts in V. fragilis
may allow the foraminifer to survive in low oxygen environments, which
reveal the important role of speciation via endosymbiosi.